What Asia said. I've mentioned before that I disagree with how most bujinkan I've seen uses space. Aside from the fact that I don't consider standing armlocks very effective, they tend to do them with a lot of space for the uke to move around in. This lowers the effectivness by many degrees. The equivalent of doing an armbar, but not squeezing your legs together, not holding the arm right up to your body and leaving it free to flap around and do counters, escapes or whatever. It's been said that the old style of jujitsu did things that way to allow you to get at your (concealed) weapons, or to provide a bit of a buffer against thiers.
Example, and OMG pics of disaster as well taken from here: (take a look) http://homepage.ntlworld.com/degsey2000/gallery.htm
Just ignore the chair for a second and look at how much space there is for the uke's arm to move around. In a real situation it's going to be pulled back and/or flopping around. It's not secure control of the arm. I've seen this type of stuff all the time, if you really wanted to use this standing armbar, you need to trap it to your chest and/or figure 4 your arms. Maybe grab your shirt to lock it in. In my book thats plain out crappling.
PS I'd be happy to be proven wrong by a good dose of alive footage but I've yet to see it.